New York's West Texas Intermediate for June delivery, was up 24 cents at $101.68 a barrel in mid-morning trade, and Brent North Sea crude for June rose 19 cents to $109.30.

Both contracts tumbled Wednesday on the US stockpiles data, which indicate softer demand at a time of robust production in the world's biggest oil consuming nation.

Stocks rose 3.5 million barrels to 397.7 million barrels for the week ended April 18, official figures showed, larger than the 2.4 million expected by analysts.

"While key economic data from US and Europe will be released this week, oil markets will continue to influenced by geopolitical events," said Sanjeev Gupta, who heads the Asia-Pacific Oil & Gas practice at professional services firm EY.

In Eastern Europe an agreement between Ukraine, Russia and Western powers in Geneva last week to pull the country from the brink of civil war appeared shaky after a gunfight on Sunday killed at least two pro-Moscow rebels.

On Wednesday, Russia hinted it will strike back if its "legitimate interests" in the former Soviet state are attacked after Kiev sent in forces to dislodge militants who have occupied government buildings there.

Moscow wants Ukraine's pro-Western government to withdraw its forces.

Ukraine, being a major conduit for Russian natural gas to Western Europe, is monitored closely by investors, who are concerned that a full-scale armed conflict will disrupt supplies and send prices skyrocketing.